1. Field of the Invention
This invention relates to a device for manufacturing semiconductor devices, and more particularly to a sputtering device for depositing insulation or metal material on a semiconductor wafer substrate.
2. Description of the Related Art
High speed sputtering devices for sputtering processes for use with semiconductor wafer substrates are known. FIG. 1 shows the internal structure of this type of high speed sputtering device. In such a high speed sputtering device, the sputtering process is repeatedly effected in a vacuum chamber VC which is kept in a low pressure condition. The pressure in vacuum chamber VC is reduced with cathode mounting CS inserted in cathode flange 11 and cathode flange 11 placed in contact with chamber wall 13 via O-ring 12. Target 16 is previously mounted on backing plate 17 in vacuum chamber VC at an angle of approximately 85.degree. which is close to a right angle with respect to the horizontal plane. Further, semiconductor wafer substrate 19 is horizontally carried into pressure-reduced vacuum chamber VC, and is transferred onto substrate holder 18 disposed in a horizontal position near target 16. Substrate holder 18 is raised, i.e., rotated upward, as shown by the arrow in FIG. 1 so as to orient the semiconductor wafer substrate 19 parallel to target 16. The sputtering process is effected after semiconductor wafer substrate 19 is disposed in the above-described preset sputtering position. In the sputtering process, a sputtered film is formed as a result of Ar.sup.+ ions striking target 16 in a magnetron-type discharging atmosphere and depositing sputtered particles emitted from target 16 on the semiconductor wafer substrate 19. In the case where a sputtered film of SiO.sub.2 is formed, for example, the sputtered film normally grows at a rate of 150 nm/min.
The sputtered particles are emitted from target 16 in various directions besides those towards wafer substrate 19 during the sputtering process. Assume that sputtered particles are deposited on chamber wall 13, for example, to form a sputtered film thereon. Then, part of the sputtered film may be peeled off from chamber wall and will drop as dust particles onto a next wafer substrate 19 which is carried in for the succeeding sputtering process, thus contaminating the surface of that next wafer substrate 19. For this reason, dome-shaped protection member or plate 15 is disposed to surround the peripheral region of target 16 in vacuum chamber VC. Protection plate 15 has opening 15A formed at the center thereof, and opening 15A is substantially closed by wafer substrate 19 and the periphery of substrate holder 18 when wafer substrate 19 is disposed in the preset sputtering position. In this case, sputtered particles emitted in directions different from those towards wafer substrate 19 will form sputtered films on protection plate 15 and the outer periphery of substrate holder 18.
When part of the sputtered film is deposited as dust particles on the next wafer substrate 19 in the sputtering process, the properties of the sputtered film formed on that wafer substrate 19 will be changed. For example, when the sputtered film is an insulating film, current leakage, reduction in the break-down voltage and the like may occur in the manufactured semiconductor device. In this case, in order to prevent part of the sputtered film from peeling off from protection plate 15 and substrate holder 18 and then dropping directly onto the next wafer substrate 19, wafer substrate 19 is disposed at an angle close to a right angle with respect to the horizontal plane.
However, in this type of sputtering device, part of the sputtered film is peeled off from protection plate 15 and substrate holder 18 and then deposited on the bottom of protection member 15. It is impossible to sufficiently prevent the deposited sputtered particles from being whirled up and attached as dust particles to wafer substrate 19 during the succeeding sputtering process. Further, since the sputtered film grows at high speed on protection plate 15 and substrate holder 18 as well as on wafer substrate 19, it becomes necessary to frequently replace or remove protection plate 15 and substrate holder 18 for cleaning. As a result, the availability or operating through-put of the sputtered device will be lowered.